redux-saga example

Usually splitting your app state into pages feels natural, but sometimes you'll want to have global state for your app. This is an example using redux and redux-saga that works with universal rendering. This is just one way it can be done. If you have any suggestions or feedback please submit an issue or PR.

This example and documentation is based on the with-redux example.

Deploy your own

Deploy the example using Vercel:

How to use

Using create-next-app

Execute create-next-app with npm or Yarn to bootstrap the example:

npx create-next-app --example with-redux-saga with-redux-saga-app
# or
yarn create next-app --example with-redux-saga with-redux-saga-app

Download manually

Download the example:

curl https://codeload.github.com/vercel/next.js/tar.gz/canary | tar -xz --strip=2 next.js-canary/examples/with-redux-saga
cd with-redux-saga

Install it and run:

npm install
npm run dev
# or
yarn
yarn dev

Deploy it to the cloud with Vercel (Documentation).

Notes

In the first example we are going to display a digital clock that updates every second. The first render is happening in the server and then the browser will take over. To illustrate this, the server rendered clock will have a different background color than the client one.

Our page is located at pages/index.js so it will map the route /. To get the initial data for rendering we are implementing the static method getInitialProps, initializing the redux store and dispatching the required actions until we are ready to return the initial state to be rendered. Since the component is wrapped with next-redux-wrapper, the component is automatically connected to Redux and wrapped with react-redux Provider, that allows us to access redux state immediately and send the store down to children components so they can access to the state when required.

For safety it is recommended to wrap all pages, no matter if they use Redux or not, so that you should not care about it anymore in all child components.

withRedux function accepts makeStore as first argument, all other arguments are internally passed to react-redux connect() function. makeStore should return a new instance of redux store each time when called, no memoization needed here. See the full example in the Next Redux Wrapper repository.

The trick here for supporting universal redux is to separate the cases for the client and the server. When we are on the server we want to create a new store every time, otherwise different users data will be mixed up. If we are in the client we want to use always the same store and hydrate it when needed. That's what we accomplish in store.js

The clock, under components/clock.js, has access to the state using the connect function from react-redux. In this case Clock is a direct child from the page but it could be deep down the render tree.

The second example, under components/counter.js, shows a simple add counter function with a class component implementing a common redux pattern of mapping state and props. Again, the first render is happening in the server and instead of starting the count at 0, it will dispatch an action in redux that starts the count at 1. This continues to highlight how each navigation triggers a server render first and then a client render second, when you navigate between pages.